JP2006171429A - Zoom lens and imaging apparatus having same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a compact zoom lens with which excellent optical performance can be obtained even if there are minor manufacturing variations in a first lens group. <P>SOLUTION: A zoom lens has the first lens group of negative refractive power and a second lens group of positive refractive power, in this order starting from the object side to an image side, and its spacing of both of the lens groups changes in zooming. The first lens group consists of an eleventh lens of negative refracting power having an aspheric shape on the faces on the object side and the image side and a twelfth lens of a positive refracting power. When the thickness on the optical axis of the eleventh lens 11 is defined as D, the optical axis direction as an X coordinate, a direction orthogonal to the optical axis as a Y coordinate, and when Y=2D and YB=3D are set, and when the X-coordinates at a height Y from the optical axis of the aspheric face on the object side and image side of the eleventh lens 11 are defined respectively as X1, X2, and the X coordinate at a height YB from the optical axis of the paraxial curvature on the object side of the eleventh lens 11 as R1B and the X coordinate at a height YB from the optical axis of the aspheric face on the object side of the eleventh lens 11 as X1B, the aspheric amount is appropriately set. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a zoom lens, and is suitable for an imaging apparatus using a solid-state imaging device such as a digital still camera, a video camera, or a surveillance camera.

  In recent years, imaging devices such as digital still cameras and video cameras have higher optical performance, and have become smaller and thinner due to remarkable technological progress of solid-state imaging devices such as CCDs used therein and downsizing of imaging devices. Therefore, there is a demand for a photographic lens that has been reduced in weight.

  Relatively high optical performance is obtained, and the entire lens system is a small zoom lens, and in order from the object side to the image side, the first lens unit L1 having a negative refractive power and the second lens unit having a positive refractive power. Thus, there is a two-group zoom lens that performs zooming by changing the air gap between the two lens groups.

  Since this two-group zoom lens can be configured with a relatively small number of lenses, it is often used for a zoom type lens system aiming at miniaturization.

  As a two-group zoom lens, a small two-group zoom lens is known in which a first lens group includes a negative lens and a positive lens, and a second lens group includes a positive lens and a negative lens (Patent Documents 1 to 3).

  Further, in such a two-group zoom lens, there is known a two-group zoom lens in which both surfaces of the negative lens on the object side in the first lens group are aspherical and aberrations are corrected well (Patent Document 4). ~ 6).

  Further, as a zoom lens compatible with a small image pickup apparatus equipped with a high-resolution image pickup device with higher image quality, a three-group zoom lens made up of lens groups having negative, positive, and positive refractive powers is known (patent). References 7 and 8).

In the three-group zoom lens, there is known a small three-group zoom lens in which the second lens group includes a positive lens and a negative lens (Patent Document 9).
JP-A-5-281470 JP-A-6-273670 Japanese Patent Laid-Open No. 11-052235 JP-A-9-33809 JP 9-33810 A JP 2002-365545 A JP 2000-147381 A JP 2000-284177 A JP 2000-9999 A

  A zoom lens used for a video camera, a digital camera, or the like is required to have a small lens system having high optical performance.

  The above-described two-group zoom lens and three-group zoom lens are suitable as a zoom lens for a wide angle of view, but the first lens in the first lens group (the lens closest to the object side) has a relative axis shift on both lens surfaces. When this occurs (when decentration occurs), the image performance tends to deteriorate significantly, and the variation in optical performance due to manufacturing tends to increase.

  In particular, this tendency was conspicuous when both surfaces of the negative lens on the object side in the first lens group are aspherical and various aberrations are to be corrected well.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a compact zoom lens capable of obtaining excellent optical performance even if there is some manufacturing variation, and an imaging apparatus having the same.

The zoom lens of the present invention includes a first lens unit having a negative refractive power and a second lens group having a positive refractive power in order from the object side to the image side, and the distance between both lens groups changes during zooming. In the zoom lens, the first lens group includes an eleventh lens having a negative refractive power in which both the object-side surface and the image-side surface are aspheric, and a twelfth lens having a positive refractive power. The thickness on the optical axis is D, the optical axis direction is the X coordinate, the direction orthogonal to the optical axis is the Y coordinate,
Y = 2D
YB = 3D
X coordinates at height Y from the optical axis of the paraxial curvature surface on the object side and the image side of the eleventh lens are R1 and R2, respectively, and the aspherical optical axis on the object side and the image side of the eleventh lens X coordinates at the height Y from the X axis are X1 and X2, respectively, the X coordinate at the height YB from the optical axis of the paraxial curvature surface on the object side of the eleventh lens is R1B, and the aspheric surface on the object side of the eleventh lens When the X coordinate at the height YB from the optical axis is X1B,
0 <| X1-R1 | / Y <2 × 10 ⁻³
1 × 10 ⁻² <| X2-R2 | / Y <9 × 10 ⁻²
1 × 10 ⁻⁴ <(X1B−R1B) / YB <5 × 10 ⁻³ is satisfied.

  According to the present invention, it is possible to obtain a compact zoom lens capable of obtaining excellent optical performance even if there is some manufacturing variation.

  Embodiments of the zoom lens of the present invention and an image pickup apparatus having the same will be described below.

  FIGS. 1A, 1B, and 1C show lens cross sections at the wide-angle end (short focal length end), the intermediate zoom position, and the telephoto end (long focal length) of the zoom lens according to Embodiment 1 of the present invention, respectively. FIG. 2A, 2B, and 2C are aberration diagrams of the zoom lens of Embodiment 1 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively. Example 1 is a zoom lens having a zoom ratio of 2.25 and an aperture ratio of about 3.28 to 5.37.

  3A, 3B, and 3C are lens cross-sectional views at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 2 of the present invention, respectively. 4A, 4B, and 4C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the second embodiment. The second embodiment is a zoom lens having a zoom ratio of 2.26 and an aperture ratio of about 3.28 to 5.37.

  FIGS. 5A, 5B, and 5C are lens cross-sectional views at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 3 of the present invention, respectively. 6A, 6B, and 6C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the third exemplary embodiment. Example 3 is a zoom lens having a zoom ratio of 2.87 and an aperture ratio of about 3.18 to 5.60.

  FIGS. 7A, 7B, and 7C are lens cross-sectional views at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the fourth exemplary embodiment of the present invention. 8A, 8B, and 8C are aberration diagrams of the zoom lens of Example 4 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively. The fourth exemplary embodiment is a zoom lens having a zoom ratio of 1.91 and an aperture ratio of about 2.88 to 4.04.

  FIG. 9 is an explanatory diagram of an aspheric shape according to the present invention.

FIG. 10 is a schematic diagram of a main part of a digital still camera (imaging device) including the zoom lens of the present invention.

The zoom lens of each embodiment is a photographic lens system used in the imaging apparatus, and in the lens cross-sectional view, the left side is the object side and the right side is the image side.

  In the lens cross-sectional views of FIGS. 1, 3, 5, and 7, L1 is a first lens group having negative refractive power (optical power = reciprocal of focal length), and L2 is a second lens group having positive refractive power. , L3 is a third lens unit having a positive refractive power. SP is an aperture stop. Examples 1 to 3 are located on the image side of the second lens unit L2, and Example 4 is located on the object side.

  G is an optical block provided for optical design corresponding to an optical filter, a face plate, a crystal low-pass filter, an infrared cut filter, and the like. IP is an image plane, and when used as a photographing optical system for a video camera or a digital still camera, a photosensitive surface corresponding to an imaging surface of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is placed. Yes.

  In the aberration diagrams, d and g are represented by d-line and g-line, respectively, ΔM and ΔS are represented by meridional image surface, sagittal image surface, and lateral chromatic aberration are represented by g-line.

  EFno is an effective F number. ω is a half angle of view.

  In the following embodiments, the zoom positions at the wide-angle end and the telephoto end are zoom positions when the zoom lens unit (second lens unit) is positioned at both ends of a range that moves on the optical axis due to the mechanism.

  In the zoom lenses of Embodiments 1 to 3 in FIGS. 1, 3, and 5, the first lens unit L1 draws a part of a convex locus on the image side during zooming from the wide-angle end to the telephoto end zoom position. The second lens unit L2 is moved to the object side.

  In the zoom lens of Example 4 in FIG. 7, during zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves so as to draw a part of a convex locus on the image side, and the second lens unit L2 Is moved to the object side so that the distance from the first lens group L1 is small, and the third lens group L3 is moved to the object side so that the distance from the second lens group L2 is large.

  In any of the embodiments, the aperture stop SP moves together with the second lens unit L2 during zooming.

  In the zoom lens of each embodiment, main zooming is performed by moving the second lens unit L2, and movement of the image point accompanying zooming is corrected by moving the first lens unit L1.

  In Examples 1 to 3, focusing is performed by the first lens unit L1. In Example 4, focusing is performed by the third lens unit L3.

  When focusing is performed with the first lens unit L1, a zooming cam locus may be formed in a step shape, and an extended locus for zooming may be used.

  In general, the two-group zoom lens shown in FIGS. 1, 3, and 5 and the three-group zoom lens shown in FIG. 7 have good optical performance over the entire zoom range, and the number of lenses is reduced. In order to reduce the thickness, it is effective to use an aspheric surface at an appropriate location in the lens system with an appropriate aspheric amount.

  In particular, it is effective to appropriately set the lens configuration of the first lens group that corrects image plane variation due to zooming, and suppresses aberration variation during zooming as much as possible.

  Therefore, in each embodiment, the first lens unit L1 has a meniscus shape in which the object side surface and the image side surface are aspherical, the absolute value of refractive power is larger than the object side surface, and the object side is convex. The eleventh lens G11 having a negative refractive power and the meniscus twelfth lens G12 having a meniscus shape having a convex surface on the object side.

  In Examples 1, 2, and 4, the second lens unit L2 is configured such that the absolute value of refractive power is larger than the image-side surface, the object-side surface is aspherical, and both lens surfaces are A convex 21st lens G21 having a positive refractive power, the absolute value of the refractive power is larger than the surface on the object side, the surface on the image side is aspheric, and the negative refractive power of the meniscus shape is negative. It consists of a 22nd lens G22.

  In this way, the two lenses constituting the second lens unit L2 have both aspherical surfaces so that aberration fluctuations associated with zooming are reduced.

  In the third exemplary embodiment, the second lens unit L2 includes a positive 21st lens having an aspherical object-side surface, a convex meniscus shape, and a negative 21st lens having a concave surface on the image side. And a 23rd lens having a positive refractive power whose both lens surfaces are convex.

  As a result, aberration fluctuations accompanying zooming are corrected satisfactorily.

  In Example 4, the third lens unit L3 includes one 31st lens having a positive refractive power.

  In each lens group, a low-dispersion material is used for a lens having a positive refractive power, and a high-refractive index, high-dispersion material is used for a lens having a negative refractive power.

  This corrects axial chromatic aberration well over the entire zoom range.

  Further, in each embodiment, when the number of lenses is ultimately reduced to about 4 to 5 as a whole, both surfaces of the negative lens on the object side having the greatest effect of aberration correction are made non-spherical and non-spherical. The spherical amount is appropriately set so as to satisfy the conditional expressions (1) to (3), and the deterioration of the optical performance due to the manufacturing error when both surfaces are aspherical is reduced.

  Next, in each embodiment, an aspheric shape provided on the object side and image side surfaces of the eleventh lens G11 of the first lens unit L1 will be described.

  FIG. 9 is a schematic diagram showing the aspherical shape of the eleventh lens G11.

  In FIG. 9, Ra and Rb are the object side and image side surfaces (aspheric surfaces) of the eleventh lens G11, respectively.

  Raa and Rbb are the paraxial curvature surfaces of the eleventh lens G11 (spherical surfaces when not aspherical).

  D is the thickness (thickness) on the optical axis of the eleventh lens G11.

In FIG. 9, the optical axis direction is the X coordinate, the direction orthogonal to the optical axis is the Y coordinate,
Y = 2D
YB = 3D
The X coordinates at the height Y from the optical axis of the paraxial curvature surfaces Raa and Rbb on the object side and the image side of the eleventh lens G11 are R1 and R2, respectively, The X coordinates at the height Y from the optical axis of the spherical surfaces Ra and Rb are X1 and X2, respectively, and the X coordinate at the height YB from the optical axis of the paraxial curvature surface Raa on the object side of the eleventh lens G11 is R1B. When the X coordinate at the height YB from the optical axis of the aspheric surface Raa on the object side of the lens G11 is X1B,
0 <| X1-R1 | / Y <2 × 10 ⁻³ (1)
1 × 10 ⁻² <| X2-R2 | / Y <9 × 10 ⁻² (2)
1 × 10 ⁻⁴ <(X1B-R1B) / YB <5 × 10 ⁻³ (3)
Is satisfied.

  The image side surface of the eleventh lens G11 is made aspherical to effectively correct coma flare, and the object side surface is also made aspherical to effectively correct distortion.

  In general, when both surfaces are aspherical, more decentration aberrations occur when the image side surface and the object side surface are decentered than when one surface is a spherical surface. Performance degradation is likely to occur.

  Therefore, in each embodiment, in order to reduce the deterioration of optical performance due to manufacturing errors while both surfaces are aspherical, the aspherical shape of the object side surface that mainly corrects distortion is set near the optical axis. The aspherical amount (deviation) is extremely small, and the peripheral part away from the optical axis has an appropriate aspherical amount.

  Conditional expressions (1) to (3) are for reducing deterioration in optical performance due to manufacturing errors while favorably correcting coma flare and distortion by making both surfaces of the eleventh lens G11 aspherical.

  Next, the technical meaning of each conditional expression will be described.

  Conditional expression (1) relates to the aspherical amount of the aspherical intermediate portion of the object-side surface of the eleventh lens G11.

  Exceeding the upper limit value of conditional expression (1) is not good because, in terms of manufacturing, when the eccentricity with the image side surface occurs, the optical performance deteriorates greatly.

  The lower limit value of conditional expression (1) is a condition that the surface shape at height Y is not a spherical surface but an aspherical surface.

  Conditional expression (2) relates to the aspherical amount of the intermediate portion of the image side surface of the eleventh lens G11.

  If the aspherical amount is too large or too small beyond the upper limit value or lower limit value of conditional expression (2), it will be difficult to satisfactorily correct coma flare in the wide angle region.

  Conditional expression (3) relates to the aspherical amount of the peripheral portion of the object-side surface of the eleventh lens G11.

  If the lower limit of conditional expression (3) is exceeded and the amount of aspheric surface is too small, barrel distortion increases at the wide-angle end, which is not good.

  If the amount of aspherical surface becomes too large beyond the upper limit value of conditional expression (3), it will be difficult to satisfactorily correct the balance of field curvature in the wide angle region.

  In each embodiment, it is more preferable to set the numerical ranges of conditional expressions (1) to (3) as follows.

0 <| X1-R1 | / Y <1 × 10 ⁻³ (1a)
2 × 10 ⁻² <| X2-R2 | / Y <6 × 10 ⁻² (2a)
5 × 10 ⁻⁴ <(X1B-R1B) / YB <3 × 10 ⁻³ (3a)
In each of the above embodiments, a filter and a converter lens are provided on the object side of the first lens unit L1, and / or a field lens or the like having a small refractive power is provided on the image side of the second lens unit L2 or the third lens unit L3. A lens group may be added.

  As described above, according to each embodiment, in order from the object side to the image side, the first lens unit having a negative refractive power and the second lens group having a positive refractive power are provided. In the zoom lens in which the lens changes, as described above, the lens configuration of each lens group, the position of the aspherical surface of the eleventh lens G11, the amount of the aspherical surface, etc. are optimally set, thereby reducing the number of lenses and In spite of achieving the shortening, a zoom lens suitable for a digital still camera has been achieved that has a zoom ratio of about 2 to 3 times, a bright, wide field angle, and high optical performance.

  Next, an embodiment of a digital still camera (imaging device) using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG.

  In FIG. 10, reference numeral 20 denotes a camera body, 21 denotes a photographing optical system constituted by the zoom lens of the present invention, 22 denotes a solid-state imaging device (photoelectric conversion element) such as a CCD sensor or a CMOS sensor that receives a subject image by the photographing optical system 21. ), 23 is a memory for recording a subject image received by the image sensor 22, and 24 is a viewfinder for observing the subject image displayed on a display element (not shown).

  The display element is constituted by a liquid crystal panel or the like, and a subject image formed on the image sensor 22 is displayed.

  Thus, by applying the zoom lens of the present invention to an image pickup apparatus such as a digital still camera, a small image pickup apparatus having high optical performance is realized.

  Next, numerical examples of the present invention will be shown. In each numerical example, i indicates the order of the surfaces from the object side, Ri is the radius of curvature of the i-th surface (i-th surface), Di is the distance between the i-th surface and the (i + 1) -th surface, Ni, ν i represents a refractive index and an Abbe number based on the d-line of the i-th member, respectively.

  The two surfaces closest to the image side are surfaces constituting the glass block G.

  The interval D = 0.0 indicates that the front and rear surfaces are joint surfaces.

In the aspherical shape, when the displacement in the optical axis direction at the position of the height h from the optical axis is x with respect to the surface vertex, x = (h ² / R) / [1+ {1- (1 + k) ( h / R) ² } ^1/2 ]
+ Ah ² + Bh ⁴ + Ch ⁶ + Dh ⁸ + Eh ¹⁰
It is represented by However, k is a conic constant, A, B, C, D, and E are aspherical coefficients, and R is a paraxial curvature radius.

“E-0x” means “× 10 ^−x ”. f indicates a focal length, Fno indicates an F number, and ω indicates a half angle of view.

Table 1 shows the relationship between the above-described conditional expressions and the respective examples.

Numerical example 1

f = 6.47-14.58 Fno = 3.28-5.37 2ω = 54.8-25.9

* R 1 = 71.623 D 1 = 1.20 N 1 = 1.859610 ν 1 = 40.3
* R 2 = 3.999 D 2 = 1.27
R 3 = 6.899 D 3 = 1.60 N 2 = 2.003300 ν 2 = 28.3
R 4 = 17.314 D 4 = Variable
* R 5 = 3.339 D 5 = 2.40 N 3 = 1.519480 ν 3 = 61.8
R 6 = -12.318 D 6 = 0.05
R 7 = 18.653 D 7 = 0.90 N 4 = 1.839740 ν 4 = 23.8
* R 8 = 5.610 D 8 = 1.30
R 9 = Aperture D 9 = Variable
R10 = ∞ D10 = 1.30 N 5 = 1.516330 ν 5 = 64.1
R11 = ∞


\ Focal length 6.47 10.52 14.58
Variable interval \
D 4 8.94 3.84 1.58
D 9 6.97 9.97 12.98


Aspheric coefficient

1 side: k = 0.00000e + 00 A = 0 B = 0.00000e + 00 C = 0.00000e + 00 D = 0.00000e + 00
E = 1.06649e-08

2 side: k = -1.42147e + 00 A = 0 B = 1.61232e-03 C = 5.75188e-05 D = -8.72454e-06 E = 5.21268e-07

5th: k = -7.19582e-01 A = 0 B = 1.35016e-03 C = 1.25052e-04 D = -6.92345e-06 E = 0.00000e + 00

Eight: k = 0.00000e + 00 A = 0 B = 5.05835e-03 C = 5.18532e-04 D = 1.69479e-04
E = -1.74682e-05


Numerical example 2

f = 6.46 to 14.59 Fno = 3.28 to 5.37 2ω = 54.9 to 25.9

* R 1 = 173.454 D 1 = 1.20 N 1 = 1.859610 ν 1 = 40.3
* R 2 = 4.050 D 2 = 1.14
R 3 = 6.868 D 3 = 1.60 N 2 = 2.003300 ν 2 = 28.3
R 4 = 18.825 D 4 = variable
* R 5 = 3.322 D 5 = 2.30 N 3 = 1.505160 ν 3 = 69.4
R 6 = -13.986 D 6 = 0.03
R 7 = 10.108 D 7 = 0.90 N 4 = 1.816130 ν 4 = 24.0
* R 8 = 4.540 D 8 = 1.30
R 9 = Aperture D 9 = Variable
R10 = ∞ D10 = 1.30 N 5 = 1.516330 ν 5 = 64.1
R11 = ∞


\ Focal length 6.46 10.52 14.59
Variable interval \
D 4 9.06 3.96 1.71
D 9 6.73 9.75 12.77


Aspheric coefficient

1 side: k = 0.00000e + 00 A = 0 B = 0.00000e + 00 C = 0.00000e + 00 D = 0.00000e + 00
E = 1.47913e-08

2 side: k = -2.82412e + 00 A = 0 B = 4.11976e-03 C = -1.18332e-04 D = 1.15515e-06 E = 2.54162e-07

5th: k = -1.00365e + 00 A = 0 B = 2.20900e-03 C = 1.07689e-04 D = -4.37671e-06 E = 0.00000e + 00

8 sides: k = 0.00000e + 00 A = 0 B = 4.64642e-03 C = 8.09817e-04 D = -6.85101e-06 E = 2.44230e-05


Numerical example 3

f = 6.45 to 18.53 Fno = 3.18 to 5.60 2ω = 54.9 to 20.5

* R 1 = 102.561 D 1 = 1.30 N 1 = 1.859610 ν 1 = 40.0
* R 2 = 5.279 D 2 = 1.30
R 3 = 7.038 D 3 = 1.70 N 2 = 1.808095 ν 2 = 22.8
R 4 = 14.336 D 4 = Variable
* R 5 = 4.150 D 5 = 1.90 N 3 = 1.768020 ν 3 = 49.2
R 6 = 14.106 D 6 = 0.00
R 7 = 14.106 D 7 = 0.80 N 4 = 2.003300 ν 4 = 28.3
R 8 = 3.765 D 8 = 0.50
R 9 = 7.542 D 9 = 1.40 N 5 = 1.696797 ν 5 = 55.5
R10 = -13.338 D10 = 0.80
R11 = Aperture D11 = Variable
R12 = ∞ D12 = 1.30 N 6 = 1.516330 ν 6 = 64.1
R13 = ∞


\ Focal length 6.45 12.49 18.53
Variable interval \
D 4 12.31 4.02 1.13
D11 8.62 13.40 18.18


Aspheric coefficient

1 side: k = 0.00000e + 00 A = 0 B = 0.00000e + 00 C = 0.00000e + 00 D = 0.00000e + 00
E = 4.97787e-09

2 side: k = -2.05352e + 00 A = 0 B = 1.48967e-03 C = 1.07476e-05 D = -2.34434e-06 E = 1.51972e-07

5th: k = 2.78578e-01 A = 0 B = -1.16603e-

Numerical example 4

f = 5.94 to 11.34 Fno = 2.88 to 4.04 2ω = 58.8 to 32.9

* R 1 = 88.391 D 1 = 1.20 N 1 = 1.850000 ν 1 = 40.1
* R 2 = 4.543 D 2 = 1.51
R 3 = 8.669 D 3 = 1.40 N 2 = 2.003300 ν 2 = 28.3
R 4 = 30.878 D 4 = variable
R 5 = Aperture D 5 = 0.70
* R 6 = 3.657 D 6 = 1.90 N 3 = 1.743300 ν 3 = 49.2
R 7 = -26.805 D 7 = 0.20
R 8 = 43.517 D 8 = 0.90 N 4 = 1.833100 ν 4 = 23.9
* R 9 = 3.727 D 9 = Variable
R10 = 13.570 D10 = 1.30 N 5 = 1.487490 ν 5 = 70.2
R11 = -39.367 D11 = variable
R12 = ∞ D12 = 1.20 N 6 = 1.544270 ν 6 = 70.6
R13 = ∞


\ Focal length 5.94 8.64 11.34
Variable interval \
D 4 10.40 4.91 1.87
D 9 2.23 3.79 5.07
D11 4.63 5.42 6.48


Aspheric coefficient

1 side: k = 0.00000e + 00 A = 0 B = 0.00000e + 00 C = 0.00000e + 00 D = 0.00000e + 00
E = 1.19382e-09

2 side: k = -4.51143e + 00 A = 0 B = 4.71670e-03 C = -2.57575e-04 D = 1.16233e-05 E = -2.35528e-07

6th: k = 3.00171e-01 A = 0 B = -1.47239e-03 C = -7.32427e-05 D = -1.16959e-05 E = -1.70612e-06

9th: k = 0.00000e + 00 A = 0 B = 5.19878e-03 C = 8.86768e-04 D = -1.39374e-05 E = 9.54031e-06

Lens cross-sectional view of the zoom lens of Example 1 Aberration diagram at the wide-angle end of the zoom lens of Example 1 Aberration diagram at the intermediate focal position of the zoom lens of Example 1 Aberration diagram at the telephoto end of the zoom lens of Example 1 Lens sectional view of the zoom lens of Example 2 Aberration diagrams at the wide-angle end of the zoom lens of Example 2 Aberration diagram at the intermediate focal position of the zoom lens of Example 2 Aberration diagram at the telephoto end of the zoom lens of Example 2 Lens sectional view of the zoom lens of Example 3 Aberration diagram at the wide-angle end of the zoom lens in Example 3 Aberration diagrams at the intermediate focal position of the zoom lens of Example 3 Aberration diagram at the telephoto end of the zoom lens of Example 3 Lens sectional view of the zoom lens of Example 4 Aberration diagram at the wide-angle end of the zoom lens in Example 4 Aberration diagrams at the intermediate focal position of the zoom lens of Example 4 Aberration diagrams at the telephoto end of the zoom lens of Example 4 Explanatory drawing of the aspheric shape according to the present invention Schematic diagram of the main part of a digital still camera

Explanation of symbols

L1: First lens group L2: Second lens group L3: Third lens group SP: Aperture IP: Image plane G: Glass block d: d line g: g line ΔS: Sagittal image plane ΔM: Meridional image plane

Claims (9)

In the zoom lens having a first lens unit having a negative refractive power and a second lens unit having a positive refractive power in order from the object side to the image side, the distance between the two lens units changes during zooming. The lens group is composed of an eleventh lens having negative refractive power and a twelfth lens having positive refractive power in which both the object side surface and the image side surface are aspherical, and the thickness of the eleventh lens on the optical axis is determined. D, the optical axis direction is the X coordinate, the direction orthogonal to the optical axis is the Y coordinate,
Y = 2D
YB = 3D
X coordinates at height Y from the optical axis of the paraxial curvature surface on the object side and the image side of the eleventh lens are R1 and R2, respectively, and the aspherical optical axis on the object side and the image side of the eleventh lens X coordinates at the height Y from the X axis are X1 and X2, respectively, the X coordinate at the height YB from the optical axis of the paraxial curvature surface on the object side of the eleventh lens is R1B, and the aspheric surface on the object side of the eleventh lens When the X coordinate at the height YB from the optical axis is X1B,
0 <| X1-R1 | / Y <2 × 10 ⁻³
1 × 10 ⁻² <| X2-R2 | / Y <9 × 10 ⁻²
1 × 10 ⁻⁴ <(X1B-R1B) / YB <5 × 10 ⁻³
A zoom lens characterized by satisfying the following conditions: The second lens group includes, in order from the object side to the image side, a 21st lens having a positive refractive power and a 22nd lens having a negative refractive power, or a 21st lens having a positive refractive power and a negative refractive power. The zoom lens according to claim 1, comprising a twenty-second lens and a twenty-third lens having a positive refractive power. 2. The eleventh lens has a shape in which an absolute value of refractive power is larger on an image side than an object side surface, and the twelfth lens has a meniscus shape having a convex surface on the object side. Or 2 zoom lenses.   4. The zoom lens according to claim 1, further comprising an aperture stop on the object side or the image side of the second lens group.   5. The zoom lens according to claim 1, wherein the second lens group includes two lenses including an aspherical surface.   The zoom lens according to claim 1, wherein the first lens group is a focusing lens group.   7. The zoom lens according to claim 1, further comprising a lens unit having a positive refractive power that moves during zooming on an image side of the second lens unit. 8.   The zoom lens according to claim 1, wherein an image is formed on a solid-state imaging device. An image pickup apparatus comprising: the zoom lens according to claim 1; and a solid-state image sensor that receives an image formed by the zoom lens.